The invention relates to a method for controlling a paced production line, and a sequence controller for operating a paced production line.
Within the scope of airplane manufacture, the processing of large airplane structural components is such that high requirements are placed on the particular production apparatus. One reason for this is that the longitudinal extension of the structural components is often greater than the longitudinal extension of the working space of a workstation assigned to the structural component.
Examples of such airplane structural components are fuselage sections or wing sections of an airplane. Typical operations to be carried out within the scope of production in this case are riveting operations, e.g. to connect frames and stringers of a fuselage section, or to connect frames and skin segments of a fuselage section or a wing. The processing of fuselage sections is the focus in this case, and is not intended to be limiting.
Various attempts have been made in the past to automate airplane production, to a partial extent at least. For example, it is known to use numerically controlled riveting robots to perform riveting operations mechanically (EP 0 593 127 181).
It is also known to use a synchronized production line to process airplane structural components such as fuselage sections, wherein the production line includes a riveting processing station with riveting robots, for instance.
In the case of a known production line, the fuselage sections are conveyed in succession through the working area of the riveting workstation in a paced manner. The riveting workstation is seamlessly connected to further workstations through which the fuselage sections likewise pass in a paced manner.
The paced production line described above is such that particularly high requirements are placed on the programming of the numerically controlled riveting robots. The main reason for this is that the fuselage sections pass through the workstations in highly diverse sequences, and therefore a different set of riveting operations must be performed depending on the production step.
Adding to the difficulty is the fact that, due to the differing longitudinal extension of the fuselage sections, the working area of the riveting workstation is typically occupied only by portions of fuselage sections, and not by entire fuselage sections. For example, the riveting workstation can be occupied by two portions of different fuselage sections.
Despite the high programming complexity involved, production lines for airplane manufacture have proven useful. However, it has been shown that actual workpiece throughput can be increased in regard to the theoretically possible workpiece throughput.